When the same promotion goes on a Page and in a Group, how do you tell which post prompted useful action? The choice is between tracking visits to the destination and evaluating activity on the two Facebook posts. Neither method makes the audiences separate; some people may see both.
Separate tagged URLs are the better fit when the decision is where qualified inquiries come from. For example, a Page post and a Group post could point to the same registration page, with a different source tag on each URL. In the destination’s analytics, compare visits and completed registrations by tag, then review whether the resulting questions are relevant. Check that both links lead to the same page and that the tags appear in the analytics report before interpreting a difference. A tag identifies the link used, not every Facebook exposure someone had before clicking it.
Native post metrics are useful when the decision is about the conversation on each surface. Check the Page post’s insights and the Group post’s visible engagement or admin insights, where available. Compare the questions people ask, not just reactions and comments: a Group discussion may answer objections in public, while a Page post may send people directly to the destination. Reach and engagement describe exposure and response on Facebook; they do not, by themselves, show how many qualified inquiries followed. Adding Page and Group reach together also risks counting people who saw both.
For a promotion posted in both places, which decision do you usually need to make afterward: where to post the next one, or which version generated more useful inquiries?